Self relighting pilot light for gas burners



Aug. 25, 1931. H. A. ATWATER SELF RELIGHTING PILOT LIGHT FOR GAS BURNERS Filed Aug. 26', 1929 v o. i

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Patented Aug. 25, 1931 UNITED STATES HARRY A. ATWATER, OF KANSAS CITY, MISSOURI SELF RELIGHTING PILOT LIGHT FOR GAS BUBNERS Application filed August26, 1929. Serial No. 388,445.

The present invention relates to pilot'gas' lighting devices for gas burners, and the primary object in View. is .to provide an improved construction of this character not only fulfilling the gas lighting function in an efficient manner, but also serving'to safeguard the pilot lighting flame and effectively shielding the same and preventing it from Q becoming extinguished,

VVith the foregoing object in view, the in vention comprises a gas lighting pilot construction in which the pilot flame is presented in its most efficient lighting relation to the main burner orifice, that is directly opposite the orifice and in the principal zone of combustion, while means is furthermore provided for maintaininga shielded zone for the pilot flame, together with flame-propagating ,;;means for maintaining the pilot flame constantly lighted in said shieldedzone and thus effecting a perpetual relighting action be tween said zone'and the pilot flame orifice and restoring the flame at the latter point as often gas it may be caused to recede in the direction '25 of the said shielded zone.

described by reference to the accompanying drawings illustrating one form of burner construction which'I have devised for embody ing the proposed improvements, after which those features and combinations deemed tobe 7 novel will'be set forth and claimed.

In the drawings- I Figure 1 is a side view parts broken away) showing a gas burner construction fitted with a pilot gas lighting device constructed in accordance with the present invention; and

Figure 2 is an elevation showing the inte rior or burner end of the same.

' In gas burner practlce, where the flow of gas to the burner is regulated in accordance with the temperature requirements for which the burner is operated, a pilot gas lighting device is required for relighting the main gas flame as often as this has been extinguished and requires to berelighted, and the principal difiiculty in such pilot lightingoperation arises whenthere is more or less abruptness in the variation of the main gas flow to the burner, inducing strong draft conditions which tendvto extinguish the pilot lighting flame. In installations where the chimney flue is also connected'directly to the burner unit, the influence of strong or gustywinds also aggravates the difficulty of maintaining the pilotflame constantly lighted.

Many expedients have been employed to overcome the difficulty which thus characterizespilot lighting devices, such as to locate v the pilot element in a dead'pocketsomewhat removed from the main burner orifice, in

order to dampen the suctional action tending to extinguish the flame. I-Iowever, such cone structions are also obj ectionable insofar, as

they delay ignition on account of the remoteness of the pilot flame from the main burner orifice, thereby incurring danger of explosive ignition, sometimes strong enough to blow open the fire door.

Such a condition 1s fullyas objectionable if not more so, than the one sought to be remedied, that of the tendency ofthe pilot flame to become extinguished and hence the desideratum in viewis a combination of features in which the pilot flame may be left in its most efiicient relation to the burnerrori- I Ifice'for ignltion purposes, and at the samek time be so shielded from draft influences as.

to prevent the lighting flamefrom being put out under even the most severe draft conditions to which-the installation might be sub-1 jected. I r I 1 y I'achieve these results by means of a burn-f: er and pilot lighting device combination in which the pilot flame orifice is presented directly opposite the'burner orifice, together with pilot flame propagating means commu nicating with a shielded pilot flame zone and serving to constantly restore the pilot flame at the pilot orifice as often as the pilot flame is caused to recede.

Referring now to the drawings in detail, this illustrates the improvement as embodied in connection with a burner structure con prising a casing or housing 5 equipped with an adjustable face plate 6 for draft regulating purposes, the oposite end of the casing or housing 5 being fitted with a casting 7 formed with a plurality of burner openings 8 within which are positioned the various tips 9 of the burners, having the main burner orifices 10 as shown in Figure 2. These burner ele ments are supplied with the necessary gas flow from a header 12 to which the gas sup ply is conducted by a pipe 14 as shown in Figure 1.

The pilot lighting structure comprises a gas tube 16 extending across the face of the casting 7 and formed with a longitudinal flame propagating slot 17, and branch pilot flame slots 18 located opposite each of the burner tips 9 and. orifices 10, as shown in Figure 2. The pilot tube 16 is carried backward.alongsidethecasing or housing 5, where.

it is fitted with a cup-shaped or hood element 20 provided with a plurality of openings or perforations 21 surrounding the extreme outer end of the flame propagating slot 17; This outer end of the pilot tube 16 and its hood element 20 are further protected by means of a casing member 22 attached to the housing, 5 by the screws 23.

Outside the casing member 22 the pilot tube is fitted with an air premixing element 25, and a suitable valve 26 as shown in Figure 1.

Inside the casing or housing 5 a wire mesh screen element 30 is provided for shieding the space back of the combustion Zones around the tips of the burners 9, this being for the purpose of preventing any flare back tending to follow the ignition of the gases around the burners for any cause, and thus providing an aditional factor of safety for the burner as well as further protection against extinction of the pilot lighting flame.

The construction as thus describedprovides a pilot flame orifice so located as to project a lighting flame directly into the path of gas issuing from. the several burner orifices 10, and these pilot flame orifices are all inrcommunication with the slot 17 constituting the flame propagating means extending from the shielded zone at the outer end of the slot 17 within the hood member 20.

As often, therefore, as the jets of flame are snuffed out at any one or more of the slots 18, and the pilot lighting flame caused to recede in the direction of the hood element 20, the flame is constantly relighted and restored asit is propagated back along the slot 17 to each one of the orifices 18, in an obvious manner.

In further explanation of this operation, it may be said that the critical point at which the pilot flame tends to become extinguished is upon the abrupt shutting off of the flow of gas to the burner elements 9, and not at the times when the gas flow to the burners is renewed. That is to say, on stopping of the gas flow to the burners, the momentary excessive draft action within the burner tends to snuff out the pilot flame, so that this inomentary extinction of the pilot flame occurs at an interval when the function of the pilot is not needed; during this interval, the pilot flame is however left still burning at the outer end portion'of the slot 17 and within the hood element 20, and as the draft action becomes neulralized by the inflow of atmospheric air the gas along the slot 17 is relighted and the pilot flames are. restored at all the orifices 18 in readiness to reignite the gas jets from the several burner orifices 10, ass-eon as the main gas flow is restoredto the burner.

The hood structure 20 and protective box or casing 22 aflord a complete shielding or protective action forthe outer zone of the pilot relighting flame, the function of the perforations 21 of the hood 20 being to maintain the pilot relighting flame well back inside the hood element regardless of the sudden or excessive draft or pressure conditions which might be created in the main firebox space in front of the burner openings 8'.

It is found by experiment that with the protective assembly shown, for shielding the outer end of the pilot relighting flame, no firebox draft conditions are apparentlypossible of development which may result in complete extinction of the relighting flame of the described pilot structure.

The premixture of the air and gas by means of the. fitting 25 results in a pilot flame which is of the true Bunsen type, always burning clear and blue and eliminating the deposit or carbon upon the pilot device. This feature however is not essential, since a plain gas flow without air premixing may be used,

depending upon the requirements of the particular installation. The various component parts of theassembly may also be of any suitable or preferred material, such as metal, lava material, or other refractory compositions, as may be found necessary'or desirable.

will thus be apparent that I have devised a practical, efficient as well as highly adapt able arrangement and construction, for fulfilling the desired purposes of the invention. The pilot lighting arrangement alfords the maximum eflieiency as regards the burner i nition, and with proper installation of the pilot tube. and shielding of the outer end of the pilotflame transmission slot, any danger of complete extinction of the relighting flame is effectually eliminated. It is also to be noted that the arrangement of the pilot structure is one which may be adapted to any particular design of burner, by simply carrying the pilot tube alongside the various burner openings, and providing a pilot jet orifice opposite said openings and thus establishing communication from said'orifice to the protected zone of the pilot flame, as in the illustration here given.

WVhile I have illustrated and described one practical form of construction for embodying these improvements, I desire to be understood as reserving the right to make all changes or modifications which may fairly fall within the scope of the following claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is: I

1. A pilot lighting construction comprising, in combination with a burner, a pilot'gas tube having a pilot flame orifice in proximity to the burner, and also formed with a continuous flame propagating slot extending from said pilot orifice to a point remote from the burner orifice, and a hood member pro- Vided with air openings surrounding the tube at the outer end of said slot for shield- I ing the pilot flame.

2. A pilot lighting construction comprising, in combination with a burner, a pilot gas tube having a pilot flame orifice in proximity to the burner, and also formed with a continuous flame propagating slot' extending from said pilot orifice to a point remote from the burner orifice, and a hood member surrounding the outer end of said slot with the open end of said hood member presented in the direction of the inner portion of the slot.

3. A pilot lighting device for gas burners comprising a tube provided with a pilot flame orifice and; with a longitudinal slot extending from the orifice to a point remote there-' from, a perforated flaring hood surrounding the outer end of said slot, and a housing encasing said hood and extendinginthe direc tion of said orlfice.

4. A pilot lighting device for gas burnerscomprising a tube provided with a pilot flame orifice and with a flame propagating structure extendingfrom said orifice to a point remote therefrom, a hood structure shielding the outer end of said flame propagating structure, and flaring in the direction of said orifice, and an air premixing device associated with the tube adjacent to said hood structure. 7

In witness whereof I hereunto afiix my signature.

HARRY A. ATWATER. 

